package com.zdp.io.nio.test1;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * @author ZhengDp
 * @Date 2024/2/27 0:13
 */
public class TimeClientHandle implements Runnable{

    private String host;
    private int port;
    private Selector selector;

    private SocketChannel socketChannel;
    private volatile  boolean stop;

    public TimeClientHandle(String host, int port) {
        this.host = host == null ? "127.0.0.1": host;
        this.port = port;
        try {
            selector = Selector.open();
            socketChannel = SocketChannel.open();
            socketChannel.configureBlocking(false);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void run() {
        try {
            doConnect();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        while (!stop) {
            try {
                selector.select(1000);
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> it = selectionKeys.iterator();
                SelectionKey key = null;
                while (it.hasNext()) {
                    key = it.next();
                    it.remove();
                    try {
                        handleInput(key);
                    } catch (Exception e) {
                        if(key != null) {
                            key.cancel();
                            if(key.channel() != null) {
                                key.channel().close();
                            }
                        }
                    }

                }
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        // 多路复用器关闭后，所有注册在上面的channel和pipe等资源都会被自动去注册并关闭，所以不需要重复释放资源
        if(selector != null) {
            try {
                selector.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

    }

    private void handleInput(SelectionKey key ) throws IOException {
        if(key.isValid()) {
            SocketChannel sc = (SocketChannel) key.channel();
            if(key.isConnectable()) {
                // 结束连接
                if(sc.finishConnect()) {
                    sc.register(selector,SelectionKey.OP_READ);
                    doWrite(sc);
                } else {
                    System.exit(1); // 连接失败，进程退出
                }
            }
            if(key.isReadable()) {
                ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                int readBytes = sc.read(readBuffer);
                if(readBytes > 0) {
                    // 写转读
                    readBuffer.flip();
                    byte[] bytes = new byte[readBuffer.remaining()];
                    readBuffer.get(bytes);
                    String body = new String(bytes,"UTF-8");
                    System.out.println("Now is : " + body);
                    this.stop = stop; // 读一次即可
                } else if (readBytes < 0) {
                    // 对端链路关闭
                    key.cancel();
                    sc.close();
                } else {
                    ; // 读到0字节，忽略
                }
            }


        }
    }

    private void doConnect() throws IOException {
        // 链接成功，注册READ事件
        if(socketChannel.connect(new InetSocketAddress(host,port))) {
            socketChannel.register(selector, SelectionKey.OP_READ);
            doWrite(socketChannel);
        } else {
            // 没有连接成功，则监听连接事件
            socketChannel.register(selector, SelectionKey.OP_CONNECT);
        }
    }

    private void doWrite(SocketChannel sc) throws IOException {
        byte[] req = "QUERY TIME ORDER".getBytes();
        ByteBuffer writeBuffer = ByteBuffer.allocate(req.length);
        writeBuffer.put(req);
        // 写转读
        writeBuffer.flip();
        sc.write(writeBuffer);
        if(!writeBuffer.hasRemaining()) {
            System.out.println("Send order 2 server succeed.");
        }

    }
}
